What is an MP3 file?
MP3 is the audio format that made portable digital music possible in the 1990s. It shrinks sound by discarding components the ear is unlikely to perceive, guided by a psychoacoustic model, so a CD track drops to roughly a tenth of its size. The bitrate, from 96 to 320 kbit/s, sets how much is kept; 192 kbit/s and above is transparent for most listeners on most equipment.
Metadata such as title, artist, album and cover art travels in ID3 tags at the start or end of the file. The last MP3 patents expired in 2017, so the format is now unencumbered, and every player, car, phone and browser supports it. Its weaknesses are age and lossiness: AAC and Opus achieve the same quality at lower bitrates, and no lossy file can be restored to the original.
When MP3 is the right choice
Strengths
- Universal playback: every device made in the last twenty-five years
- Small files with adjustable bitrate
- ID3 tags carry titles, artists and album art
Limitations
- Lossy: quality is lost permanently at each encode
- Less efficient than AAC and Opus at the same bitrate
- Unsuitable as a master for editing or archiving
How to open an MP3 file
Every media player, browser and phone plays MP3. For editing, open it in Audacity or a DAW, but export the result to WAV or FLAC and only encode an MP3 as the final step to avoid stacking losses.
How to convert an MP3 file
MP3 to WAV produces an uncompressed file for editing or for equipment that needs PCM, MP3 to AAC or MP3 to M4A target Apple devices, and MP3 to FLAC wraps the same audio in a lossless container. From the other side, Video to MP3 pulls the soundtrack out of a video, and Compress Audio lowers the bitrate of a large file.